1. Field of the Invention
The present invention relates generally to means for inherently improving the structural integrity of filamentary tectonic tape-like strips or sheet materials and of shaped structural components which are fabricated therefrom by a precisely controlled lamination thereof.
More particularly the invention relates to the composition and fabrication of tectonic tapes, strips and sheet material employed in the lamination of structural shapes, hereinafter referred to as filamentary composite strips and structural shapes as defined by J. E. Ashton, J. C. Haplin and P. H. Petit in their publication: PRIMER ON COMPOSITE MATERIALS, chapter 1, pages 1 and 2, Technomic Publishing Company, Inc., Stamford, Conn. 1969, which are characterized by an inherent capability for providing protection against cataclysmic disintegration of the structure thus fabricated by the arrestment of any fast propagating fracture that may develop resultant from extrinsically imparted damage or sustained overloading of the tape or fabricated shaped article.
2. Description of the Prior Art
Conventional filamentary composite tapes, strips and fabricated tectonic shapes have little or no tendency toward nucleation and growth of through cracks under cyclic loading. However, the brittle static mode of failure exhibited by such filamentary composite strips and shapes creates problem in the structural integrity of these materials, and particularly in the cataclysmic disintegration or complete structural failure thereof in the event damage is inadvertently incurred or sustained overloading is experienced. It is well recognized, particularly in the aerospace industry, that this problem of static mode failure in advanced filamentary composite materials exists. Prior to the present invention, however, no known means had been devised to employ elastic fracture mechanics for predicting behavior of such materials under sustained loading in uniaxial tension. Such loading results in fast propagation of a rupture, as may be caused by external damage. Neither has a dual modulus, heterogeneous, tape-like strip material having residual strength capacity in excess of limit design load, even when damaged, been evolved or proposed by those having skill in the art.